How do U.S. government “encounters” at the border differ from net increases in the unauthorized resident population?
Executive summary
"Encounters" are administrative events recorded by Customs and Border Protection when someone is apprehended, found inadmissible at a port of entry, or expelled under special authorities; they do not map one‑to‑one to people who become long‑term unauthorized residents, and can substantially overcount or undercount true net population change depending on repeat crossings, expulsions, got‑aways and interior dynamics [1] [2] [3]. Net increases (or decreases) in the unauthorized resident population are demographic estimates that combine inflows and outflows over time — including entries without encountering officials, legal overstays, removals, voluntary departures and natural demographic changes — and are estimated by agencies and researchers with very different data and assumptions than encounter tallies [4] [5] [6].
1. What an “encounter” actually measures and why it is an imperfect proxy for people staying in the U.S.
An encounter in CBP statistics is an event: Title 8 Border Patrol apprehensions, Office of Field Operations inadmissibles at ports, and expulsions under Title 42 are all counted as encounters, and a single person can generate multiple encounters in a single year or be expelled without ever entering the resident population [1] [7] [2]. Agencies and analysts explicitly note encounters are events, not unique individuals, so the raw encounter total can substantially overstate the number of distinct people seeking to remain because of repeat attempts and deterrence‑driven returns [2] [3]. Conversely, encounters can undercount inflows because some people enter without ever meeting an official — the so‑called “got‑aways” or entries without inspection — which many estimates place in the tens or hundreds of thousands depending on the year and methodology [4] [5].
2. How demographers and economists construct net population change from many moving parts
Net change in the unauthorized resident population is a demographic calculation, not a law‑enforcement headcount: it starts with estimated inflows (legal entries, parole releases, entries without inspection) and subtracts exits (removals, voluntary departures, returns, deaths and net emigration) and adds net changes from visa overstays; agencies like the CBO and researchers at Brookings and regional Federal Reserve authors use multiple administrative series and survey microdata to assemble these flows and estimate net population trends [4] [5] [6]. Those estimates explicitly exclude many expedited border removals from ICE removal tallies or treat detentions as temporary exits from civilian population estimates, which complicates direct comparisons to CBP encounter reports [5] [6]. The result: a year of high encounters can coincide with little net population growth if most encounters are expulsions or repeated apprehensions of the same people, while a year of low encounters can still see net increases via overstays or unobserved crossings [2] [4].
3. Why policy changes make encounters and net population estimates diverge
Policy shifts such as Title 42 expulsions, parole programs, or interior enforcement drives change the composition of encounters and the fate of those encountered: Title 42 produced millions of immediate expulsions that appear as encounters but did not necessarily create a resident population, while parole programs can convert border interactions into temporary lawful presence and later court cases that show up differently in demographic series [2] [8]. Analysts note that tightening enforcement and cancelling parole programs have pushed unauthorized inflows to pandemic‑era lows in some recent estimates, but those same policies also make estimating “got‑aways” and overstays more uncertain, so encounters fall even as the pool of long‑term unauthorized residents changes more slowly [6] [9].
4. Practical consequences for public debate and policymaking
Conflating encounters with net unauthorized population change creates predictable errors in policy debates: encounters are useful for operational metrics and immediate resource planning at ports and sectors (CBP uses them for enforcement statistics), but they should not be treated as direct measures of how many unauthorized immigrants live, work and pay taxes in the U.S., which are the quantities CBO and demographers estimate for budget and social planning [7] [4]. Different actors have incentives to emphasize one series over the other — border agencies highlight encounter reductions as operational success, while economists focus on net population because it underpins labor market and fiscal analysis — so interpreting either number requires attention to methodology and the hidden flows both series miss [10] [5].
5. Bottom line and reporting limits
Encounters measure border control activity and are prone to double‑counting and policy‑driven artifacts; net unauthorized population change measures resident stocks and requires modeling inflows and outflows that encounters alone cannot provide [2] [4]. The available reporting makes clear both series matter for different questions, and current data limitations — especially around entries without inspection and the treatment of rapid expulsions — mean watchdogs and policymakers must read encounter data alongside CBO, academic and migration‑policy estimates to understand real changes in the unauthorized resident population [5] [6] [4].